A long time ago, most people who used webmail were cybercafe-frequenting, patchouli-scented trustafarians backpacking through Europe. Just about everybody else used a real e-mail client that ran on the desktop.

But times change. With Google's launch of Gmail in 2004, webmail became powerful enough to replace a desktop client. Since then, Microsoft's Hotmail and Yahoo Mail have added features to catch up, but Gmail is still my favorite; I've been using it as my primary work and personal e-mail for most of the past three years.

It's also the favorite of many other home and business users. Gmail had 49 million users in September, according to comScore, making it the second-most-popular webmail service behind Yahoo Mail. What's more, Gmail is built into Android smartphones, so it's a natural for Android users.

Gmail is powerful and flexible, but not everybody's using it to its full advantage. You can beef it up by applying these tips and tools to customize and extend it.

Priority Inbox is a great new feature from Gmail that uses algorithms to determine which e-mails in your in-box are most important. It works very much like a spam filter. Priority Inbox looks for similarities between a new incoming message and messages you've received in the past. If the new e-mail is similar to messages you've previously read and replied to, Gmail filters the message into the Priority Inbox.

If new e-mail resembles messages you've ignored, Gmail figures it isn't as important and leaves it in your regular in-box.

Gmail: Priority Inbox Use Priority Inbox to see your most important mail first.

Priority Inbox is a great feature because it saves you time sifting through e-mail. Your most important messages bubble to the top of your in-box, where you can give them immediate attention. Less important mail drifts down lower in your in-box, where you can deal with it when you have time.

By default, Gmail groups together all messages with the same subject line; Gmail figures they're all part of the same conversation. Messages with identical subject lines are hidden under the most recent message; click it to see the rest.

The conversations view was a revolutionary feature when Gmail launched, and also divisive -- some users (including me) love it, while others can't stand it. Opponents say that it's too difficult to separate unread messages in a thread from new messages that they haven't read yet; they have to wade through already-read messages to find the new e-mails.

Google threw a bone to the haters in September and gave users a setting to switch off conversations. Here's how to do it: Go to Settings --> General --> Conversation View to switch conversations on and off.

Gmail: Conversations on and off Hate the conversations view (shown at top)? Switch it off (bottom).

Google Apps administrators will need to activate the "Enable pre-release features" option in the Google Apps control panel to allow users to switch between conversations and an unthreaded view (more on how to do that later in the story).